Distillation op tar and the like



April 2e.* 19z1.

1,626,588 W. B. DAVIDSON ET AL DISTILLATION 0F TAR AND THE LIKE Filed April 23, 1926 Patented Apr. 26,

" was w tfraivrfnnown AVIDSON, ARTIiUn CUMMING ,MIonIE; zinnlniinnsr WALTER MUDDIMAN, or E C s rLEb Y'NE, ENGLAND. I 1' a f 'ff} insTIL A'J:101v or TARANnrnE LIKE.

Applicat ion filed a rnas, 192s, seriai No.*104,16$, and in r at Britain A rn 1-,, 1925.

This invention relatesto the dehydration and partial distillation of tar orthe like,

and has for its object to provide improved means for obtaining adistillatewhich is free from contamination 'due to frothing or priming of the tar or like the distillation process.

substance during It not infrequently occurs thatduring the dehydration of certain tars, notably low,

temperature tars, the contents of the still have a tendency-to, froth or prime with resulting contamination of the distillate and in some cases serious loss and dangermay be incurred due to sudden excessive prim ing and boiling over of'the still contents;

The presentfinvention' consists in the elimination of undue frothing of tar-or the like, during the process of." distillation, by

subjecting the 'fr'oth to 5 contact with a hot surface whereby gthe froth is immediately 7 broken up and subsides. The invention furthermore consists in the provision of" *meanswhereby the dehydration process may progressat a maximum self regulatingv rate consistent with quietfand continuousoperation. f The hot surface which may be of anysuitable design is maintainedat a vapour space above the normal level of the temperatm'e above that of the originating" froth by the circulation of steam or other,

heating fluid. through suitable channels associated with the heating surface.

In carrying the invention into effect a plurality of tubes may conveniently constitute'the hot surface andthrough which the heating fluid is passed at a [suitable temperature, said tubes being arranged in the substance undergoing distillation. This arrangement is particularly adaptable for use in that type of still:in which heat is applied to the contents immediately below the surface, since, according to our invention,

we may connect the froth subduing surface 'with the contents heating Ineansin such. a manner that the same heating fluid may be caused to initially traverse the froth subduing surfaceand then "pass through the contents heating means to a final outlet.

The froth, which contains a considerable amount of water isbroken ,upflupon mar ing contact with the hot surface and causes momentary condensation of some of the heating fluid with the result thatv less heat is conveyed to the contents heating means I elevation A.A. v Y

' and temporary retardation of the -dehy dra-" tion occurs until thefroth subsides.

accompanying drawings which illustrate one practicalembodiment-asapplied to a 'stlllof the type described in the specificationof British Patent Noj 196399 and of which Figure 1 is a side elevational 'vi'erv In order that the inventionmay bemore" clearly understood reference is madeto the of the apparatus and Figure 2 a sectional v of Figure 1 'through the l line Referring now to these drawings the nu sponding series of horizontally extending W tubes '4; are located immediately below the tar level 3 and connected by bends or other suitable connections with vertically: disposed :tubesJ Steamis admitted by way of avalve 6 to a steam supply chamber 7 in l isv caused to passtthrough the individual hydrating tubes 4 and in so doing imparts suflicient heat to the {tar to effect the boiling and distillation. s a

A similar chamber 8 is provided atthe delivery ends of the tubes 4 from which the condensed steam may be led through a pipe 9 to asteain trapor separator. The system of tubes 2, 5, 4 asshown in the illustrated embodiment is of a horizontal U shape formation, thereby obviating troubles due to expansion of the steamtubes upon heating; we

further precaution may be taken if desired by the provision of supporting rollers excommunication ;with the inlet ends of the tubes 2, said tubes being arranged inparal- I 'lel 'sothat steam issuing from the chamber to tending across the still atright angles to the tubes. An inlet 10for crude tar is located at the bjottomofthe still and is supplied from any suitable pressuremeans, suchas a constant l6VBl'1S6IVQ1I',-W1tl1 tar preferably not pl'eheated. The dehydrated tar leaves the still through a delivery pipe 11 and may be conducted therefrom for subsequent treatment or storage. Ayapour pipe 12 is provided in communication with the'vapourspace above the upper series of tubes 2 whereby the vapours formed by the distillation may be discharged from the still.

The hot surface constituted by the closely pitched steam tubes 2 forms an efficient means for breaking up the froth contacting therewith. tar obtained by the low temperature carbonization of coal it is desirable to maintain the steam passing through the tubes 2 at a temperature of about 120 to 160 C. and if no froth is formed the heating tubes 4 Will cause adequate boiling of thetar to effect distillation. If however froth is formed, as soon as it is broken up by contact with the hot tubes 2 a certain amount of the steam within the said tubes will be condensed, thus causing less heatto be containedv in the tubes 4.

It may be seen therefore that frothin of the tar is accompanied by a corresponding diminution in temperature of the tubes 4,

such conditions persisting until the froth subsides whereupon less steam is condensed withinthe tubes 2 and consequently more heat is conducted to the heating tubes 4. In thisimanner and by suitably regulating the flow of steam tl'irough the valve 7 the systemtmay be causedto operate so that just suflici'ent heatmay be generated in the still as to ensure quiet and continuous operation under varied conditions: notwithstanding the formation of froth.

Althoughwe have shown in the embodiment a hotsur'face constituted by a plurality of steam tubes itshoulcl be noted that while the hereinbefore described arrangement/forms a-convenientmanner of adaptation the invention may equally apply to In the case of the distillation of modified shape and construction of the hot surface.

What we claim and desire to secure by Letters Patent is Apparatus for distilling liquids which froth when heated, comprising a liquid container having an inlet pipe near the bottom, an outlet pipe for maintaining a predetermined liquid level within the container, whereby a vaper space ismai-ntained within the container above the level of 'the liquid, a plurality of froth disintegrating heating tubes within said vapor space, a plurality of liquid heating tubes positioned slightly below the normal liquid level, each of said heating tubes being directly connected with one of the froth disintegrating tubes, said froth disintegrating tubes having no connections within the container but being connected with a common inletheader exterior-1y of the container and said liquid heating tubes having no connections within the containerbut beingconnected by a common outlet header exteriorly thereto, Whereby a supply of heating fluid may becaused to circulate through said froth disintegnatving tubes and also through said immersed heating tubes, the supply of heat;being;te1;nporarily retardedupon engagement offroth with the froth disintegrating tubes andathe heatingfiuid being discharged from eachio'f said immersed tubes througlrthe common outlet header.

. In witness whereof we affix our signatures.

\VILLIAM BROWVN DAVIDSON. ARTHUR CU-MMING' MICHIE. ERNEST WALTER MUDDI -MAN. 

